A daring form of surgery that transplants tiny amounts of pig brain tissue into people seems to benefit some patients with severe Parkinson's disease, a new study shows. The findings raise the prospect that such operations might help patients in whom traditional drug therapy no longer has much effect.
Parkinson's disease strikes when brain cells die and the brain fails to make adequate quantities of dopamine, a neurotransmitter required for nerves to deliver brain signals to muscles. For their study, the first of its kind, researchers enrolled 10 patients who had tremors, muscle rigidity, or other symptoms of advanced Parkinson's. To replace the lost cells, researchers injected the brain of each patient with 12 million cells taken from the area of fetal pigs' brains where dopamine is made.
One year after the transplants, which occurred in 1995 and 1996, mobility and performance of simple tasks had dramatically improved in three patients and was moderately better in three others, says study coauthor Jonathan H. Dinsmore of the biotechnology firm Diacrin in Charlestown, Mass. The condition of the other four patients held steady or declined slightly, he says. The report appears in the March 14 NEUROLOGY.
The pig-cell recipients achieved an average improvement after one year comparable to that reached by patients who had received brain tissue taken from human fetuses. Three-year data on the pigcell recipients show that some patients have maintained benefits from the treatment, Dinsmore told SCIENCE NEWS.
While transplantation of animal tissue avoids the ethical and legal questions clouding use of human fetal cells, animal tissue poses health risks. To minimize them, the team used only embryonic tissue from pigs raised in controlled conditions and screened it for bacteria and viruses. Up to 5 years after surgery, no porcine pathogens are detectable in any of the patients, Dinsmore says. …